Should I be offended?

So here's the deal, I come from a very heavy Greek heritage, being only 3rd generation out of Greece and around Halloween I'm always very confused. There is always a pop of costumes of Greek goddesses (Aphrodite, Athena, Hera, etc.) and other figures from Greek mythology. Even Spartan costumes manage to pop up into the mix. It never seems to be anyone from actual Greek heritage dressed in these costumes either. I just don't see where dressing like something from Hispanic/African/Asian culture isn't ok but dressing as something from Greek culture is fine. Thoughts?